Clive Chitty

As a SAP Assessor I was very interested to spot your discussion. A few comments: 1. The price RichS was quoted can only be described as rock-bottom. I would struggle to do a decent job on anything much bigger than a shoe-box for that much money. Pricing does depend strongly on size and complexity, and I always ask to see drawings before quoting. EPC's are subject to random audits according to a strictly enforced sampling regime, and must be within 4% of the auditors independent calculation, so an assessor who cuts too many corners won't stay in business for very long. 2. SAP Assessments are always based on drawings and notes, and never on a site visit. 3. SAP is designed for the general housing market, and can only be described as a "blunt instrument" when applied to anything like Passivhaus. Even the most conscientious of assessors will struggle to find ways to accurately represent some of the technologies used and performance levels achieved, using the approved software. If the manufacturer or installer hasn't seen a need to get what they produce tested and approved by BRE, then the SAP assessor may have no alternative than to use some very inferior default figures. You need SAP to show Building Control that you are following Building Regulations - but don't expect it to tally with the performance predicted in the Passivhaus design documents! 4. A SAP rating over 100 isn't silly - it means you are getting enough energy from renewables to more than cover your needs, and on average have some to spare (eg to feed back into the grid). 5. Whether a SAP rating and EPC fairly represents an actual dwelling comes down to the honesty of the builder/developer and how well Building Control do their job. My impression is that some Building Inspectors are much better than others. I'm sure there is some abuse of the system, but generally an EPC has to be a good idea, as it may be the only thing that gives prospective house buyers a handle on the likely running costs of their shiny new home.